Because infection is responsible for the majority of morbidity and mortality associated with all forms of cancer and its treatment, approaches to management of such infections will be investigated. The primary approach to infection will be the study of techniques to prevent infection in patients exposed to a high risk of infection associated with cancer treatment. Four major modalities of infection prevention will be investigated. First, the use of prophylactic antibiotics administered either systemically or orally. Second, the use of non-specific immunostimulation to enhance host resistance to infection. Thirdly, the administration of granulocyte replacement transfusion therapy to granulocytopenic patients. Fourthly, the improvement in reverse isolation, or protected environment procedures for isolating the patient both from the endogenous and exogenous organisms. These will be investigated individually and in the possible combinations to detect additive or synergistic effects.